This invention relates to a method and apparatus for mounting components and more particularly to an improved method and apparatus for more precisely picking up components to be mounted on a substrate.
A wide variety of types of apparatus have been proposed for picking up small components such as integrated circuits, resistors or the like, and mounting these components at an accurate location on a substrate. The components are normally picked up by a pick-up device such as a vacuum pick-up nozzle from a feeder station. When the components are picked up, their orientation relative to the pick-up device cannot be accurately controlled so as to insure precision mounting. Therefore, it has been proposed to provide various ways in which the orientation of the component, as picked up by the pick-up device, is determined, and then the mounting position is corrected to accommodate errors in the pick-up location.
The co-pending application of the inventor hereof, entitled "Method For Mounting Components And An Apparatus Therefor," Ser. No. 08/073,741, filed Jun. 8, 1993, and assigned to the assignee hereof, discloses a method whereby optically it is possible to determine the orientation of a component picked up by the pick-up device by rotating the component and measuring the projected length of the component in two (2) angular positions. From these measurements, the actual location of the component can accurately be determined and the corrective factors calculated.
In the above mounter, the pick-up point of the pick-up nozzle is typically preset by the program. Often, however, this preset location will not precisely correspond to the position of the tape feeder on the component supply section due to a mechanical error by the tape feeder or a drive error by the mounting apparatus.
Unfortunately, the greater the magnitude of this error, the more likely that there will be an error in the correction. In addition, the need to correct for this error slows the mounting process. Finally, if the error magnitude is great, the pick-up device may not properly pick-up the component.